@工厂模式
class Beijing:
    def printreslut(self):
        print("ok")
class Shanghai:
    def printreslut(self):
        print("shanghaiss")
def get(name="beijing"):
    result=dict(beijing=Beijing,shanghai=Shanghai)
    return result[name]().printreslut()
def  send(name):
    if name=="beijing":
        print("ok")
    else:
        print("找不到你要的答案")
if __name__=='__main__':
    send('shenzhen')
    try:
        get('shenzhen')
    except KeyError as e:
        print("找不到你要的答案")